This invention relates generally to universal joints and, more particularly, to yoke configurations for use with universal joints of the double Cardan type.
Intermediate shafts used in automobile steering columns require one or more universal joints to maneuver the column around various mechanical components. Operating angles of such universal joints have increased as vehicle engine compartments have become smaller and as rack and pinion steering systems have replaced recirculating ball steering systems. To accommodate the increased operating angles, simple universal joints with a single pivotable cross-pieces joining two shafts have been replaced by double Cardan universal joints that have two pivotable cross-pieces and a mechanism to ensure that the operating angle is distributed equally between the two pivotable cross-pieces.
Such double Cardan universal joints have two opposite end yokes, with a hub for joining each yoke to a shaft and branched arms defining a fork opposite the hub. Two pivotable cross-pieces are mounted in the branched arms of the yokes and link the yokes to a coupling yoke that transmits torque between the two shafts. A central ball joint, comprising a spherical ball fixed on one yoke and a sleeve for receiving the spherical ball fixed to the other yoke, controls the angle of the connecting yoke with respect to each shaft. Such universal joints are well known in the art. An example of a double Cardan universal joint of this type is illustrated in U.S. Pat. No. 5,820,467.
Although such designs have been effective, the high cost of forming the yokes and other components of such double Cardan universal joints has limited their use. Typically, such yokes require a casting, forging or assembly of a multipiece blank, along with machining and other manufacturing processes that add significantly to the cost of the universal joint. Accordingly, there is a need for an improved design that is suitable for manufacturing yokes for such double Cardan universal joints more simply, but without comprising the quality of the resulting universal joint.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
In one aspect of the invention, this is accomplished by providing a method of making a yoke for a double Cardan universal joint. The method comprises cutting a metal sheet to provide an elongated blank having five regions defined along the length of the elongated blank, the defined regions being a central region, two end regions, and an intermediate region between the central region and each of the two end regions. The elongated blank is bent such that the two end regions overlap and provide a mounting for a shaft and such that a pivot member to be mounted on the central region of the elongated blank will be in alignment, axially, with respect to the shaft.
In another aspect of the invention, this is accomplished by providing yoke for a double Cardan universal joint, the yoke being made according to a particular method.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.